hw/char/bcm2835_aux.c

   1 /*
   2  * BCM2835 (Raspberry Pi / Pi 2) Aux block (mini UART and SPI).
   3  * Copyright (c) 2015, Microsoft
   4  * Written by Andrew Baumann
   5  * Based on pl011.c, copyright terms below:
   6  *
   7  * Arm PrimeCell PL011 UART
   8  *
   9  * Copyright (c) 2006 CodeSourcery.
  10  * Written by Paul Brook
  11  *
  12  * This code is licensed under the GPL.
  13  *
  14  * At present only the core UART functions (data path for tx/rx) are
  15  * implemented. The following features/registers are unimplemented:
  16  *  - Line/modem control
  17  *  - Scratch register
  18  *  - Extra control
  19  *  - Baudrate
  20  *  - SPI interfaces
  21  */
  22
  23 #include "qemu/osdep.h"
  24 #include "hw/char/bcm2835_aux.h"
  25 #include "qemu/log.h"
  26
  27 #define AUX_IRQ         0x0
  28 #define AUX_ENABLES     0x4
  29 #define AUX_MU_IO_REG   0x40
  30 #define AUX_MU_IER_REG  0x44
  31 #define AUX_MU_IIR_REG  0x48
  32 #define AUX_MU_LCR_REG  0x4c
  33 #define AUX_MU_MCR_REG  0x50
  34 #define AUX_MU_LSR_REG  0x54
  35 #define AUX_MU_MSR_REG  0x58
  36 #define AUX_MU_SCRATCH  0x5c
  37 #define AUX_MU_CNTL_REG 0x60
  38 #define AUX_MU_STAT_REG 0x64
  39 #define AUX_MU_BAUD_REG 0x68
  40
  41 /* bits in IER/IIR registers */
  42 #define TX_INT  0x1
  43 #define RX_INT  0x2
  44
  45 static void bcm2835_aux_update(BCM2835AuxState *s)
  46 {
  47     /* signal an interrupt if either:
  48      * 1. rx interrupt is enabled and we have a non-empty rx fifo, or
  49      * 2. the tx interrupt is enabled (since we instantly drain the tx fifo)
  50      */
  51     s->iir = 0;
  52     if ((s->ier & RX_INT) && s->read_count != 0) {
  53         s->iir |= RX_INT;
  54     }
  55     if (s->ier & TX_INT) {
  56         s->iir |= TX_INT;
  57     }
  58     qemu_set_irq(s->irq, s->iir != 0);
  59 }
  60
  61 static uint64_t bcm2835_aux_read(void *opaque, hwaddr offset, unsigned size)
  62 {
  63     BCM2835AuxState *s = opaque;
  64     uint32_t c, res;
  65
  66     switch (offset) {
  67     case AUX_IRQ:
  68         return s->iir != 0;
  69
  70     case AUX_ENABLES:
  71         return 1; /* mini UART permanently enabled */
  72
  73     case AUX_MU_IO_REG:
  74         /* "DLAB bit set means access baudrate register" is NYI */
  75         c = s->read_fifo[s->read_pos];
  76         if (s->read_count > 0) {
  77             s->read_count--;
  78             if (++s->read_pos == BCM2835_AUX_RX_FIFO_LEN) {
  79                 s->read_pos = 0;
  80             }
  81         }
  82         if (s->chr) {
  83             qemu_chr_accept_input(s->chr);
  84         }
  85         bcm2835_aux_update(s);
  86         return c;
  87
  88     case AUX_MU_IER_REG:
  89         /* "DLAB bit set means access baudrate register" is NYI */
  90         return 0xc0 | s->ier; /* FIFO enables always read 1 */
  91
  92     case AUX_MU_IIR_REG:
  93         res = 0xc0; /* FIFO enables */
  94         /* The spec is unclear on what happens when both tx and rx
  95          * interrupts are active, besides that this cannot occur. At
  96          * present, we choose to prioritise the rx interrupt, since
  97          * the tx fifo is always empty. */
  98         if (s->read_count != 0) {
  99             res |= 0x4;
 100         } else {
 101             res |= 0x2;
 102         }
 103         if (s->iir == 0) {
 104             res |= 0x1;
 105         }
 106         return res;
 107
 108     case AUX_MU_LCR_REG:
 109         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_LCR_REG unsupported\n", __func__);
 110         return 0;
 111
 112     case AUX_MU_MCR_REG:
 113         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MCR_REG unsupported\n", __func__);
 114         return 0;
 115
 116     case AUX_MU_LSR_REG:
 117         res = 0x60; /* tx idle, empty */
 118         if (s->read_count != 0) {
 119             res |= 0x1;
 120         }
 121         return res;
 122
 123     case AUX_MU_MSR_REG:
 124         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MSR_REG unsupported\n", __func__);
 125         return 0;
 126
 127     case AUX_MU_SCRATCH:
 128         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_SCRATCH unsupported\n", __func__);
 129         return 0;
 130
 131     case AUX_MU_CNTL_REG:
 132         return 0x3; /* tx, rx enabled */
 133
 134     case AUX_MU_STAT_REG:
 135         res = 0x30e; /* space in the output buffer, empty tx fifo, idle tx/rx */
 136         if (s->read_count > 0) {
 137             res |= 0x1; /* data in input buffer */
 138             assert(s->read_count < BCM2835_AUX_RX_FIFO_LEN);
 139             res |= ((uint32_t)s->read_count) << 16; /* rx fifo fill level */
 140         }
 141         return res;
 142
 143     case AUX_MU_BAUD_REG:
 144         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_BAUD_REG unsupported\n", __func__);
 145         return 0;
 146
 147     default:
 148         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
 149                       __func__, offset);
 150         return 0;
 151     }
 152 }
 153
 154 static void bcm2835_aux_write(void *opaque, hwaddr offset, uint64_t value,
 155                               unsigned size)
 156 {
 157     BCM2835AuxState *s = opaque;
 158     unsigned char ch;
 159
 160     switch (offset) {
 161     case AUX_ENABLES:
 162         if (value != 1) {
 163             qemu_log_mask(LOG_UNIMP, "%s: unsupported attempt to enable SPI "
 164                           "or disable UART\n", __func__);
 165         }
 166         break;
 167
 168     case AUX_MU_IO_REG:
 169         /* "DLAB bit set means access baudrate register" is NYI */
 170         ch = value;
 171         if (s->chr) {
 172             /* XXX this blocks entire thread. Rewrite to use
 173              * qemu_chr_fe_write and background I/O callbacks */
 174             qemu_chr_fe_write_all(s->chr, &ch, 1);
 175         }
 176         break;
 177
 178     case AUX_MU_IER_REG:
 179         /* "DLAB bit set means access baudrate register" is NYI */
 180         s->ier = value & (TX_INT | RX_INT);
 181         bcm2835_aux_update(s);
 182         break;
 183
 184     case AUX_MU_IIR_REG:
 185         if (value & 0x2) {
 186             s->read_count = 0;
 187         }
 188         break;
 189
 190     case AUX_MU_LCR_REG:
 191         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_LCR_REG unsupported\n", __func__);
 192         break;
 193
 194     case AUX_MU_MCR_REG:
 195         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MCR_REG unsupported\n", __func__);
 196         break;
 197
 198     case AUX_MU_SCRATCH:
 199         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_SCRATCH unsupported\n", __func__);
 200         break;
 201
 202     case AUX_MU_CNTL_REG:
 203         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_CNTL_REG unsupported\n", __func__);
 204         break;
 205
 206     case AUX_MU_BAUD_REG:
 207         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_BAUD_REG unsupported\n", __func__);
 208         break;
 209
 210     default:
 211         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
 212                       __func__, offset);
 213     }
 214
 215     bcm2835_aux_update(s);
 216 }
 217
 218 static int bcm2835_aux_can_receive(void *opaque)
 219 {
 220     BCM2835AuxState *s = opaque;
 221
 222     return s->read_count < BCM2835_AUX_RX_FIFO_LEN;
 223 }
 224
 225 static void bcm2835_aux_put_fifo(void *opaque, uint8_t value)
 226 {
 227     BCM2835AuxState *s = opaque;
 228     int slot;
 229
 230     slot = s->read_pos + s->read_count;
 231     if (slot >= BCM2835_AUX_RX_FIFO_LEN) {
 232         slot -= BCM2835_AUX_RX_FIFO_LEN;
 233     }
 234     s->read_fifo[slot] = value;
 235     s->read_count++;
 236     if (s->read_count == BCM2835_AUX_RX_FIFO_LEN) {
 237         /* buffer full */
 238     }
 239     bcm2835_aux_update(s);
 240 }
 241
 242 static void bcm2835_aux_receive(void *opaque, const uint8_t *buf, int size)
 243 {
 244     bcm2835_aux_put_fifo(opaque, *buf);
 245 }
 246
 247 static const MemoryRegionOps bcm2835_aux_ops = {
 248     .read = bcm2835_aux_read,
 249     .write = bcm2835_aux_write,
 250     .endianness = DEVICE_NATIVE_ENDIAN,
 251     .valid.min_access_size = 4,
 252     .valid.max_access_size = 4,
 253 };
 254
 255 static const VMStateDescription vmstate_bcm2835_aux = {
 256     .name = TYPE_BCM2835_AUX,
 257     .version_id = 1,
 258     .minimum_version_id = 1,
 259     .fields = (VMStateField[]) {
 260         VMSTATE_UINT8_ARRAY(read_fifo, BCM2835AuxState,
 261                             BCM2835_AUX_RX_FIFO_LEN),
 262         VMSTATE_UINT8(read_pos, BCM2835AuxState),
 263         VMSTATE_UINT8(read_count, BCM2835AuxState),
 264         VMSTATE_UINT8(ier, BCM2835AuxState),
 265         VMSTATE_UINT8(iir, BCM2835AuxState),
 266         VMSTATE_END_OF_LIST()
 267     }
 268 };
 269
 270 static void bcm2835_aux_init(Object *obj)
 271 {
 272     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
 273     BCM2835AuxState *s = BCM2835_AUX(obj);
 274
 275     memory_region_init_io(&s->iomem, OBJECT(s), &bcm2835_aux_ops, s,
 276                           TYPE_BCM2835_AUX, 0x100);
 277     sysbus_init_mmio(sbd, &s->iomem);
 278     sysbus_init_irq(sbd, &s->irq);
 279 }
 280
 281 static void bcm2835_aux_realize(DeviceState *dev, Error **errp)
 282 {
 283     BCM2835AuxState *s = BCM2835_AUX(dev);
 284
 285     if (s->chr) {
 286         qemu_chr_add_handlers(s->chr, bcm2835_aux_can_receive,
 287                               bcm2835_aux_receive, NULL, s);
 288     }
 289 }
 290
 291 static Property bcm2835_aux_props[] = {
 292     DEFINE_PROP_CHR("chardev", BCM2835AuxState, chr),
 293     DEFINE_PROP_END_OF_LIST(),
 294 };
 295
 296 static void bcm2835_aux_class_init(ObjectClass *oc, void *data)
 297 {
 298     DeviceClass *dc = DEVICE_CLASS(oc);
 299
 300     dc->realize = bcm2835_aux_realize;
 301     dc->vmsd = &vmstate_bcm2835_aux;
 302     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
 303     dc->props = bcm2835_aux_props;
 304 }
 305
 306 static const TypeInfo bcm2835_aux_info = {
 307     .name          = TYPE_BCM2835_AUX,
 308     .parent        = TYPE_SYS_BUS_DEVICE,
 309     .instance_size = sizeof(BCM2835AuxState),
 310     .instance_init = bcm2835_aux_init,
 311     .class_init    = bcm2835_aux_class_init,
 312 };
 313
 314 static void bcm2835_aux_register_types(void)
 315 {
 316     type_register_static(&bcm2835_aux_info);
 317 }
 318
 319 type_init(bcm2835_aux_register_types)